I don't know about others, but when I say "larger health bar", I simply mean it to be larger than the power bar, for example. Makes it easier for a healer to keep an eye on health, while "dimming" power because you don't care as much about it. I've recently gone back to raiding on my chanter, so I'd value a larger power bar.
Also, the clicky buttons of your UI are fairly big IMHO, you can safely make them a lot smaller. Probably even halve their size.
Some people like big interfaces, some like small interfaces. Pleasing both isn't easy. I'd probably argue that us raiders like small interfaces because we have to keep an eye on lots of information all the time, but we still like to have more than a 2x2 box in the middle of the screen of actual "game"
